Add processor heartbeat management and improve health check functionality

- Introduced processor heartbeat configuration in environment variables and Docker setup.
- Implemented heartbeat publishing in the processor worker.
- Enhanced health check endpoint to include processor availability status.
- Updated frontend components to handle processor unavailability messages.
- Added legacy return functionality in the upload panel.

faceai/docker-compose.yml

@@ -28,6 +28,7 @@ services:
       FACEAI_RUNTIME_ROOT: /data/runtime
       FACEAI_UPLOAD_ROOT: /data/runtime/uploads
       FACEAI_LOG_ROOT: /data/logs
+      FACEAI_PROCESSOR_HEARTBEAT_GRACE_MS: 20000
     volumes:
       - .:/app
       - ./logs:/data/logs
@@ -37,7 +38,7 @@ services:
     ports:
       - "3001:3001"
     healthcheck:
-      test: ["CMD-SHELL", "wget -qO- http://127.0.0.1:3001/health | grep -q '\"ok\":true'"]
+      test: ["CMD", "node", "-e", "fetch('http://127.0.0.1:3001/health').then(async (response) => { const payload = await response.json().catch(() => ({})); if (!response.ok || payload.ok !== true) { console.error(JSON.stringify(payload)); process.exit(1); } }).catch((error) => { console.error(error.stack || error.message); process.exit(1); })"]
       interval: 10s
       timeout: 5s
       retries: 6
@@ -71,6 +72,8 @@ services:
       FACEAI_PKL_ROOT: /data/pkl
       FACEAI_WORKER_CONCURRENCY: 2
       FACEAI_MATCHER_BINARY: /app/bin/face_matcher
+      FACEAI_PROCESSOR_HEARTBEAT_INTERVAL_MS: 5000
+      FACEAI_PROCESSOR_HEARTBEAT_TTL_SECONDS: 20
     volumes:
       - .:/app
       - ./logs:/data/logs